Why is the proportion of confirmed cases and asymptomatic infections so disparate? Shanghai CDC responds

Xinhua News Agency, Shanghai, March 22 (Reporter Yuan Quan) At the press conference on the prevention and control of the new coronary pneumonia in Shanghai held on the 22nd, Fu Chen, director of the Shanghai Center for Disease Control and Prevention, confirmed the recent diagnosis of new coronary pneumonia in Shanghai. The proportion of cases and asymptomatic infections is relatively disparate.

From 0:00 to 24:00 on the 20th, Shanghai added 24 new confirmed cases of local new coronary pneumonia and 734 asymptomatic infections; from 0:00 to 24:00 on the 21st, Shanghai added 31 new local confirmed cases of new coronary pneumonia and 865 asymptomatic infections.

Fu Chen explained that according to national standards, asymptomatic infections refer to those who are positive for the etiological test of the new coronavirus but have no relevant clinical manifestations. The proportion of asymptomatic infections among immigrants, high-risk occupational groups, etc. is related to etiological characteristics, human resistance, vaccination, and discovery methods.

Fu Chen introduced that the new coronavirus in Shanghai’s current round of outbreaks is the BA.2 subtype of Omicron variant, which is characterized by strong concealment, fast transmission, short incubation period and no clinical symptoms. Typical, at the same time, the average age of the infected people in this round of epidemic is 40.6 years old, the median age is 40 years old, and the proportion of people under 60 years old accounts for 84.5%. Strong, the proportion of asymptomatic is also higher.

At present, the total number of doses of the new crown vaccine in Shanghai has exceeded 55 million, more than 22 million people have completed the whole course of vaccination, and more than 11 million people have completed the booster vaccination. The entire population has been vaccinated against the new crown, and the population immunity is increasing, and the proportion of asymptomatic infections will also increase.

In addition, asymptomatic infections are mainly found through nucleic acid testing, population screening, etc. Recently, Shanghai has carried out regional grid nucleic acid screening, and a certain number of positive infections have been found, including Asymptomatic infections in the incubation period and early stage.

Fu Chen reminded that with the development of the disease, some asymptomatic infected people will show clinical symptoms and turn into confirmed cases. Asymptomatic infected people are also contagious, and they should wear masks in daily life , Wash hands frequently, reduce gatherings, maintain social distance, develop a good lifestyle, and strengthen personal protection.